#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <stdlib.h>
int cmp(const void* p1, const void* p2)
{
	return *(int*)p1 - *(int*)p2;
}
int main()
{
	int arr[11];
	int* p = arr;
	int sz = sizeof(arr) / sizeof(arr[0]);
	for (int i = 0; i < sz - 1; i++)
		scanf("%d", &arr[i]);
	arr[sz - 1] = '\0';
	qsort(arr, sz - 1, sizeof(arr[0]), cmp);
	while (*p)
	{
		if (*p == *(p + 1))
			p = p + 2;
		else
		{
			printf("%d\n", *p);
			p++;
		}
	}
	return 0;
}